Craters

, Lake and Peninsula County, Alaska
Aniakchak is an extant volcano. The caldera formed during a major eruption in 1645 B.C. The most recent eruption was in 1931. Surprise Lake within the caldera is the source of the Aniakchak River, a National Wild River.

, Alaska
Fisher caldera is 11 km wide by 18 km long. It is one of at least three volcanoes on Unimak Island that have been active in historical time, with the most recent activity recorded in August of 1830.

, Arizona
The site was formerly known as the Canyon Diablo Crater, and scientists generally refer to it as Barringer Crater in honor of Daniel Barringer who was first to suggest that it was produced by meteorite impact.

, Coconino County, Arizona
SP Crater is a cinder cone volcano. The base of the cone is 3,900 feet (1,200 m) across and 820 feet (250 m) tall. It has a lava flow that extends for four miles to the north.

, Coconino County, Arizona
Sunset Crater was named for its brilliantly colored scoria deposits mantling the cone. Having erupted sometime between 1080 and 1150 AD, it is the youngest of the more than 550 vents of the vast San Francisco volcanic field.